With the current trends of the flat and thin display devices, the display devices have been gradually changed from Braun tube type (including a cathode ray tube (CRT)) into flat display devices such as a plasma display panel (PDP) or a liquid crystal display device (LCD).
Among the above-mentioned display devices, PDP is a display device in which fine cells arranged between thin glass plates are filled with a discharging gas. The light emission from the PDP is generated by making gas discharge with forming a strong electric field in the gas layer by using electrodes. As a result, ultraviolet rays are generated, and self-light emission occurs by the generated ultraviolet rays.
Also, LCD is a display device for displaying a desired image by filling liquid crystal materials between thin glass plates and forming an electric field in every pixel of an image to be displayed so as to control orientations of liquid crystal in different directions.
A conventional Braun tube-type display device includes a glass tube whose surface is somewhat spherical in shape due to the limitation on the shape of a shadow mask (of course, the flat Braun tube has been provided with the recent development of a tension type mask, but the old Braun tube has been produced to considerable numbers) and is integrally connected to lateral face. However, the PDP or LCD includes two facing glass plates and an image displaying material (gas or liquid crystal), and an edge side between the two glass plates is encapsulated with suitable materials. Therefore, the PDP or LCD is advantages in comparison with a conventional Brown tube-type display device since it has a thin thickness and superior flatness.
However, panels in the display devices such as the PDP or LCD, are very fragile when receiving impacts due to their inherent characteristics. That is, the conventional display devices are formed of relatively thicker glass, and have a slightly bulged surface to ensure a high vacuum that is formed inside the display devices as described above in the Braun tube, but the PDP or LCD does not have shape that the conventional display devices have. Therefore, the panels may be broken when a certain level of external impacts are applied to the panels since glass substrates installed in the panels have a thin thickness and a flat shape in the case of the PDP or LCD. In addition to the PDP or LCD, OLED or other light emitting devices have been used for the display devices, or many products including a conventional window may be broken when impacts are given to the products, and therefore the products need to be protected from the impacts.
In order to solve the above problems, glass-type filters in which a variety of functional films are attached to a semi-tempered glass have been developed and used in the art. However, the use of such semi-tempered glass results in the deteriorated optical characteristics of the display devices, and also runs right against the recent trends to lighten the weight of display device. Therefore, it is not also desirable to reinforce panels in the display devices in the above-mentioned manner.
Accordingly, there is an urgent need to develop a method for effectively reinforcing a display device without using the reinforcement method in which a glass substrate is used as described above.